Electrical condenser



Jan. 3, 192s'. 1,655,022

G. w. PICKARD ELECTRICAL CONDENSER Filed Oct. 8. 1920 2 Sheets-Sheet 1- G. W. PICKARD ELECTRICAL CONDENSER Filed Oct. 8. 1920 Mfr areal/1MM V 9 Jan. 3, 1928.

Patented Jan. 3, 1928.

UNITD STATES. PATENT oFFicE.;

(il-IISZEENIJEAK IEl WHITTIER lICIKAIR'D,` OF -NEWTON CENTER, MASSACHUSETTS, ASSIGNOB T WIRELESS SPECIALTY APPARATUS COMPANY, OF BOSTON, MASSACHUSETTS, A

eoBronATI'oN or NEW YORK.

iinriorniciin i ooNnnN'sEn.

Application aied catcher a, i920. serial No.. 415,472.

This invention relates to electrical condensers and in particular to high tension condensers for general use4 but especially adapted for use in radio communication.

# vIn condensers heretofore in use, the condenser stack generally has been arranged in its casing vertically,- resting on the bottom and secured in `the casing by means of a'.

.cover of insulating material which has provedy unsatisfactory for the purpose of maintaining the high pressure necessary for the proper operation of the condenser which requires that the sheets of dielectric, genreallymica, and foil, preferablytinfoil, be

maintained in intimate contact. Such condenser comprises a number of lsections connected in series, the lov;r otential section being connected to the casing, while the high potential section is" connected to a suitable "'terminal project-ing through the cover.

The object of the present invention is to provide a compact, durable condenser in which the stack is constantly maintained i -under the highest practical compression.

`V is to p rovidea construction in which the use of insulating material under strain for the purpose of compression (of the con'- denser stack, as heretofore, as of a top cas' ingcover of insulating material) is avoided and in which the sides of the casing receive the thrust of compression, compactness being obtained by reducing to a minimum the cated at the ends'gof the stack connecting it with the `casing,fz and also particularly4 a in the middle of .-the stack and connected In particular the object of the invention z composing the stack l to end transversely of the casing, articularlyxfthe invention remetal pressure and connector plate located withA a condenser terminal projecting thru the enclosing casing to, the exterior thereof but suitably insulated therefrom.'

The invention consists further in dtails of construction and combination of parts hereinafter more particularly described and claimed. v

In the accompanying drawings, which form a part of the specification,

` Figure 1 is a sectional elevation Vof one embodiment of the invention.

Fig. 2 is a -sectional elevation thereof taken on the line 2-'2'of Fig. 1, looking in the directionl of the arrows.

Fig. 3 is a sectional elevation of a modified form of the invention in which the cas-A ing is shown inclined. l

Fig. 4 is a sectional elevation of the construction shown in Fig. 3 taken on the line 4r-'4; of Fig. 3. looking in -the direction' of .or parallel to the bottom of the casing; that is, the individual sheets of foil and dielectric are arranged vertically with reference to the bottom and spaced therefrom sutliciently for purposes of insulation. Stack 2 may consist of onev or two parts, such as parts 3 and 4, arranged end parts being connected in parallel at adjacent ends 5 centrally of the' casing and each part 3 and'i comprising a plurality of sections 6 -connected in series atalternate ends 7 and provided with separators 8 between the sections rojecting beyond adjacent unconnected en s and beyond the connections. Means is provided in the, present invention which co-operates with the opposite sides 2 of the A casing for clamping the stack in place within the casing and exerting higli pressure on the stack to maintain the sheets of dielectric and the two ioo foil in intimate contact. This means in the embodiment of Fig. 1 comprises a pair of surfaces of the sheets.

.I nected in parallel.

the adjacentends ofthe shorter stacks metallic wedges 9 and 10 which are placed centrally within the casing and in the present embodiment between and engaging the inner adjacent ends of the two parts 3 and 4 of stack 2 and having a surface suiiiciently great to cover the adjacent surfaces of the adjacent ends 5 of the two parts 3 and 4. The outer ends 11 and 12 of the stack 2 engage the vertical opposite walls 2a of the casing 2 substantially as shown, the stack being highly compressed between the wedges 9 and 10 and the sides of the casing, the pressure being transmitted uniformly over the entire surface of the sheets. In assembling the stack in the casing, after the wedge 9 is in place, the wedge 10 may be driven in by any suitable means compressing either the part 3 or 4, or both, against the sides 2 of the casing` 1, which should be sufficiently strong for this purpose, thus exerting a high pressure on the stack and maintaining the sheets of foil and dielectric in intimate contact uniformly throughout their surfaces, the pressure being applied at'right angles to the The inner ends 5 of the two parts 3 and 4 or the innermost sections 6 are electrically connected to the wedges 9 and 10 which constitutes a high potential point intermediate of the stack and suiliciently spaced from the casing 1 for insulation purposes. A suitable lead 13 connects these wedges 9 and 10 to a high potential terminal 14 projecting through insulating cover 15, whereby the two parts 3 and 4 are con- The outer ends 11 and 12 of the stack 2 are at substantially the same potential and electrically connected to the casing 1, which constitutes the low potential terminal whereby the stack may be clamped through the instrumentality of the Sides of the casing without the introduction of insulation for insulating the ends from each other, although it is practicable there to employ under compression any of the commonly used insulating materials.

In effect, thestack 2 comprises two-separate stacks or parts 3 and 4, each part hav- 1ng its low potential end near the casing and its high potential point centrally of the casing. Compression is maintained' on each stack or parts 3 and 4 by the wedges 9 and 10 which exert a thrust on opposite walls of the casing through the two stacks or parts 3 land 4,. and support the stack in its position electrically spaced from the metal of the casing. .Also the intermediate members 9, of Fi s. 1 and 3 and member 24 of Fig. 5 are usefu mechanically in distributing the aplied pressures morev uniformly thruout a ong stack by reason of their effective mechanic "l'splittin-g of the entire stack into two shorter'gimechanically separated stacks; and `such intermediate members are useful electrically in providing' means for connecting to the exterior terminal 14, the surfaces of such intermediate metal members constituting practical means for the soldering thereto ofl the foils projecting from sections of the two shorter stacks adjoining the intermediate 7U metal member; and such intermediate metal members are useful thermally in being good thermal conductors absorbing heat transmitted thereto longitudinally from both adjacent short lengths of the entire stack. 7r

It will thus be seen that there is pigj/ vided, a. stack in two parts 3 and 4, the tw parts being connected in parallel and the/individual sections of each part being connected in series with the outer ends 1l and 80 12 at the same potential as that of the casing, whereby the casing may be utilized as a part of the clamping means without excessive insulation, or insulation under tensile strain, while the central portion 9, 10 of the 85 clamping means, i. e., the part most remote from the casing and hence suitably insulated therefrom via the stack itself, is the high potential point of the condenser.

The stack or the parts 4 and 5 thereof may 9U be manufactured and built up in any suitable manner, though it is preferable that they be built up of alternate sheets of foil of opposite polarity, preferably tinfoil, and dielectric, preferably mica, with proper precautions for removing air and moisture and highly compressing the stack during manufacture. The process may be carried out by coating each sheet with melted wax such as paraffin during the building, then submitting the 1U" stack of sheets to high pressure of the order of thousands of pounds to force out the wax, then separating the stack into sections and making the connections, then applying high pressure to the stack and treating it with wax, as more fully described in my co-pending application Serial Number 380,- 919, filed May 12, 1920. After the stack as above treatedis placed in the condenser casing'l in the manner above described, the cas- 110 ing may be illedjwith any suitable embedding wax 16 such as paraiiin or a mixture of paraffin and carnauba wax, either with or without the aid of vacuum and the cover is thenapplied.

The vform disclosed in Figs. 3 and 4 is slightly different from the form disclosed in Figs. 1 and 2, inasmuch as the casing 1l is there shown as having inclined-sides 2, and

between the outer ends 11a and 12a`of the 120 stack 2c and casing 1a are placed wedges orr` abutments 17 and 18 of any suitable hiaterial such as metal, which also may be integral with the casing, for the purposeof providin a fiat surface for uniformly engaging the '125 en sY 11L and 12t of the stack throughout their surfaces. f l

` Referring to^Fig, 4,- it will be seen that the sheets of mica 19.and foil 20 of the sections 6a taper downwardly with their long edges 130 In Fig.l 5 is illustrated a modified form of clamping means for maintaining the stack 2d under compression within the casing 1C having sides 2". In this embodiment, the stack 2x is in two parts 3c and 4, electricall connected-in arallel, each part being l Y ma e up of a plurality of sections 6c connect- 20 ed in series and provided with separators 8 between the sections asvabove described. The stack 2r1 is placed horizontally or transversely within the casing in the same man? ner as the stacks above described with the inner ends 5 of the parts 3c and 4 facing each other and'separated by and engaging a central metal plate or pressure member 24 of about the same surface area as .the ends ofthe stack and to which the adjacent'sections are electricallyconnected in parallel forming al centrall located high' potential point of the con enser. The outer Aends 11 and 12c of the stack or parts thereof are provided with metal pressure plates 25 and 26 engaging the same, interposed between the ends of the stack and the casing and Aforming abutments for adjusting screws 27 and 28 interposed between the plates 25 and 26 and the casing, extending through the opposite sides 2 of casing 1 and engaging the abutments or pressure plates 25 and 26; The pressure plates 25 and 26 are provided with recesses 29 into which the inner ends of the screws lit for holding the plates and stack in place within the casing and electrically separated therefrom. The outermost sections or outer endsy l1c and 12 of the stack 2d or partsare at the same and equal potential,I and electrically connected to the casing which constitutes the low potential terminal.. This electrical connection to the casing may be made through. the pressure plates 25 and 26 as shown or by separate leads to the cas veys the thrust to the side wall of the'c-asing'. The stack shown in-Fig. 5 may be treated with wax to remove air, etc., in any suitable manner, such as above described, and lthe final -pressure is applied` by the screws 27 and 28 after the stack is placed in the casing. The casing may then be filled with any suitable embedding wax as above described. The metal plate 24 which constitutes the high potential point of the condenser and is locatedcentrally within the casing is connected by a conductor 13c to a high potential terminalllc, as above described, projecting through a suitable insulating cover 15c of any suitable material having the requisitel insulating qualities.

The condenser embodying this invent-ion,

maintains the sheets of foil and dielectric in intimate contact under high pressure securing at thel same time compactness and durability. In the embodiments illustrated, theouter ends of the stack or parts are at equal and low potential and electrically connected to the casing which constitutes the low potential terminals, while the intermediate art of the stack constitutes the high potential part thereof. Thus there is provided a condenser which `is strong and compact and in which the stack is maintained under a high pressure without the necessity of excessive insulation in the clamp to insulate the ends from each other.

It is to be understood that the 'invention is not limited to the embodiments and is claimed as new and what it is desired to` rotect by Letters Patent of the United tates is as follows.

1. In an electrical condenser, the combination with a stack of sheets of dielectric material and conducting foils, of a boxlike metal casing therefor the walls of which are held substantially rigid by the casing-bottom; a condenser terminal extending -from the stack out through the casing ,at a oint intermediate the walls thereof and insulated from the metal of the casing; the stack being positioned in the casing 'with its ends facin opposite rigid casingfwalls and with the e ges of its sheets spaced from the metal of the Acasing .to be electrically insulated therefrom when the condenser is connected in use in its circuit; and pressure devices located inside the casing between the stack and the opposite .casing-walls, said pressure devices-being constructed and arranged to cause the stack to tend tol force, said casinglil() walls away from one another and by the l service conditions of compression and position separated from the metal of the casing; and said pressure devices being movable independently of one another to permit centralizing the stack with respect to said condenser terminal, in the act of putting the stack under its service compression.

2. In an electrical condenser of the stacksheet type, the combination with a box-like casing having metal bottom and sides, of a series Sectional stack arranged transversely therein with its ends adjacent to and electrically connected with two opposite metal sides oi the casing and its sides spaced from the bottom and the other sides of the casing;

. a condenser terminal extending from the stack through and insulated Jfrom the metal casing; a conducting member of substantial thickness, mass and stiffness interposed in' the middle of the stack andhaving flat opposite surfaces engaging the adjacent ends of the two portions of the stack on opposite sides of such conducting member, said conducting member being electrically connected to said condenser terminal; and a device located between an outer end of the stack and an adjacent side of the casing and holding the stack under compression and in position suspend-ed in the casing.

3. In an electrical condenser ot the stacksheet type, a box-like metal casing, a condenser terminal extending rom the stack and insulated from said casing, the stack' being in two parts located endl to end inside the casing; an intermediate conducting member of substantial thickness, mass and stitfness and located between the parts of the stack, to which conducting member like-- the stack, and means co-operating with the Civ sides of the casing for compressing the stack therein, said means comprising pressure devices located respectively between'the stacks ends and casing-sides and movable independently of one another permitting localization ofI the stack in the casing in the direction of the length of the stack.

' 5. In an electrical condenser, the combi: nation with a stack of sheets of dielectric material and conducting foils, 'of a boxlike metal casing therefor the walls otwhich are held substantially rigidy by the bottom;

said stack bein positioned in such casing to have its ends acing opposite walls thereof and the edges of its sheets spaced from the bottom and the other walls of the casing; and means located insidethe casing and between the ends of said stack and said oppositerigid walls and movable by one another by way of the intervening stack,.for maintaining the sheets of the stack in intimate contact with one another over substantially their entire surfaces by holding them together under compression, said means being constructed and arranged to bear against said opposite walls respectively and to engage substantially the entire areas of the ends of the stack and to cause the stack to tend to torce said walls a'way from one. another; said means being constructed and arranged to be independently movable t0- ward one another, while bearing against said opposite walls, into a position wherein the sheets of the stack are maintained under the desired high compression; and said means being constructed and arranged cooperatively with said walls to support the stack in its said position separated :trom the metal casing.

6. In an electrical condenser, the combination with a stack of sheets of dielectric 4'inaterial and conducting foils, of a boxlike casing therefor the walls of which are held substantially rigid bythe bottom; the .stack being positioned in said casing with its ends facing opposite walls thereof; and means for maintaining the sheets of the stack in intimate contact with one another over substantially their entire surfaces by holding them together under compression, said means comprising pressure plates engaging substantially the entire areas oi the two ends of the stack and movable by one another by way of the stack, and means engaging each pressure plate, bearing against the respective opposite casing-walls, and constructed to cooperate with the pressure plates to support the stack in position away from the other walls of the casing and to permit the respective place-s of-engagement with the pressure plates to be independently movable each toward the other wall while such engaging means continues to bear against said walls, whereby the platesor either of them may be brought into final position to cause the stack to tend to force said opposite` walls away from one another and thereby maintain the sheets of the stack in intimate Contact with one another under the desired high compression.

7. In an electrical condenser, a casing, a stack within the casing in a'plurality ofi125 parts arranged end,` to end, a conductingmember of substantial thickness, mass and stiti'ne'ss,'and mounted between the parts and receiving the thrust thereof at the inner ends, and means co-operating with the casing and the outer ends of the stackfor compressing the parts against said conducting member.

8. In an electrical condenser,` the combination with a stack comprising sheets of dielectric material and conducting foils, of a boxlike casing therefor the walls of which are held substantially rigid by the bottom, the stack being positioned in the casing with its ends facing opposite casing-walls; and means for maintaining the sheets ofl the stack in intimate contact which comprises three members, one of which has substantial thickness, mass and stiffness and is located between two parts of the stack and the other two of which are located respectively between the ends of the stack and opposite casing-walls, said three members being constructed and arranged to cause the stack to tend to force said'walls away from one another and thereby itself and its parts be held' under compression between such walls.

9. In an electrical condenser, a casing, and a stack within the casing in a plurality of parts arranged end -to end and having an intermediate conducting member of substantial thickness, mass and stiffness, and located between the parts, said stack-parts beingV compressed between the walls of the casing and said conducting member.

10. In an helectrical condenser, a casing, a stack within the casing in a plurality of parts, an intermediate pressure member between the parts, pressurefplates'l'ponA thev outer ends of the parts and screws threaded into the casing'and engaging the pressure plates for compressing the stack against the intermediate pressure mem'ber and adjusting pressure member in opposite directions.

11. In an electrical condenser, a metal casing having an insulating; portion, a stack withinv the casing comprising parts having sections connected in series, an intermediate metal pressure member 'between the parts to which the inner ends ofthe parts are electrically connected,- pressure plates on the outer ends of the parts, screws vthreaded in the casing and engaging the pressure plates for compressing the parts and adjustl ing them in opposite directions, the outer ends of said parts being electrically `connected to the casing, and a terminal projecting through said insulating portion and connected to said intermediate member.

12. InI an electrical condenser, aA casing having a terminal therein, a stack in a plurality of parts arranged end to end within the casing, an intermediate metal pressure member of substantial thickness between the parts to which like terminals ofthe parts adjacent said member are electrically 'connected, said pressure member being electrically connected to said casing terminal, and means for compressing the stack and adjusting the same with the intermediate member -in opposite directions to properly position the same within the casing.

13.V In--an electrical condenser,` a metal casing, a stack arranged within the casing and having a plurality of parts each comprising sections connected in series, a met-al member of substantial thickness and located between said parts to which the inner ends of the parts adjacent said member are electrically connected, said parts being comrpressed between said metal member and the -walls of the casing respectively, the outer ends of said parts adjacent the casing being electrically connected thereto, and a,ter minal projecting through said casin insulated therefrom and electrically( connected to said intermediate metal member.

GREENLEAF WHITTIER PICKARD. 

